i'm new in here..i just have a problem instaling GTA4 weapons mod.And yes, i'm using OpenIV. i watched the tutorial how to use it in youtube. i did everything correctly , i put the files in weapon.img and then i click Rebuild, i also click edit mode first..But when i play the game..nothing happens,nothing change , all weapon is default. i think my issue is i'm getting this window when i click Rebuild ( see pic ) : i think that window shouldn't pop up.Because every tutorial i watched in youtube ..they just simply click Rebuild and that's it.Please Help me if you know what is wrong.

The rebuild option is in SparkIV, openIV has one but it shouldn't be used for installing mods. All you need to do is enter the edit mode and replace the gun you want to replace (by right-clicking it and selecting 'replace' followed by selecting the new file). OpenIV automaticly saves so you can exit the program right after replacing the weapon. Make sure you replace both the .wdr and .wtd file (with the new .wtd and .wdr file).

Just forget about the rebuild option all together, even when using SparkIV it's completely unnecessary to use that option (even though many readme's do indeed mention it)

Oh and btw, update your game to atleast 1.0.4.0. (1.0.7.0 is the latest)